A place for software, hardware and DSP-based audio gizmos. All things code and the hardware that runs it. Time and amplitude are described in bits and pieces here. Links to interesting gizmos and software.

I think you can find MS-DOS 6.22 readily available for download.
Microsoft apparently dropped their ftp site for it but I recall them recently announcing that it would become public domain.
I don't know about the version from this site but you might try it: https://www.kirsle.net/msdos

I am very interested in this topic! Forget the 'code"..I am a hardware guy. **

1. My first contact with "digital control" of an analog desk was 20+ years ago with an Otari Concept One (desk was from the Sound Workshop collective..Michael Tapes...in Happauge (?) NY...Otari had purchased the company). Digital control of bus routing, Aux pre/post, etc via a center section. However, all of the control signals into the analog I/O console modules were static control lines which flipped various FETs...no "clock hash" inside the channels.

2. Current contact is a Neve Capricorn digital desk. Digital lines are controlling the gains in the mic preamps. It looks like a bunch of latches toggle "DG" chips which flip around resistors in feedback loops.

QUESTION! How to keep all of that digital control sh!t from feeding into our itty-bitty mic level circuits...

I've glanced at the THAT chip info...with the SPI control interface. Sheesh...chattering digi-lines tenths of inches from from "my precious" mic levels....

<g>

Bri

** Back in the 1980's, a friend of mine owned a Pawnshop in Okla. City, and he got me started writing a rather complex app totally designed for the Pawnshop biz. DOS based using Clipper (a compiled Superset of dBase). I sold 10+ installs of that system to Pawnshops in Oklahoma...another "War Story" lol!

** Sidebar: writing "escape codes" for Epson dot matrix printers which had to bang out 3-part paper hard-copies for the Pawnshop, customer and the Cop Shop AND align onto pre-printed multi-part paper forms approved by the Oklahoma "pawnshop government gods".

Professional audio and video systems design/installation/maintenance.www.BrianRoth.com

brianroth wrote:I am very interested in this topic! Forget the 'code"..I am a hardware guy. **

1. My first contact with "digital control" of an analog desk was 20+ years ago with an Otari Concept One (desk was from the Sound Workshop collective..Michael Tapes...in Happauge (?) NY...Otari had purchased the company). Digital control of bus routing, Aux pre/post, etc via a center section. However, all of the control signals into the analog I/O console modules were static control lines which flipped various FETs...no "clock hash" inside the channels.

2. Current contact is a Neve Capricorn digital desk. Digital lines are controlling the gains in the mic preamps. It looks like a bunch of latches toggle "DG" chips which flip around resistors in feedback loops.

QUESTION! How to keep all of that digital control sh!t from feeding into our itty-bitty mic level circuits...

I've glanced at the THAT chip info...with the SPI control interface. Sheesh...chattering digi-lines tenths of inches from from "my precious" mic levels....

<g>

Bri

** Back in the 1980's, a friend of mine owned a Pawnshop in Okla. City, and he got me started writing a rather complex app totally designed for the Pawnshop biz. DOS based using Clipper (a compiled Superset of dBase). I sold 10+ installs of that system to Pawnshops in Oklahoma...another "War Story" lol!

** Sidebar: writing "escape codes" for Epson dot matrix printers which had to bang out 3-part paper hard-copies for the Pawnshop, customer and the Cop Shop AND align onto pre-printed multi-part paper forms approved by the Oklahoma "pawnshop government gods".

Carefully... Inside the chip is reasonable, and when you change the gain that alters the analog signal some too, while not that bad with zero-cross coordinated gain switching.

Care is required in the very front end mic pre to A/D layout, once it's in the digital domain things are easier.

I was working on a digital controlled analog "Automatic Mixer" (share gain between multiple active mics automatically) with an analog mixer company. The microprocessor digital control simplified the gain sharing calculations, and using digital pots for line level audio gain control sounded surprisingly good (to me) even without zero crossing coordination (I left hooks to add that if needed). Unfortunately they abandoned the project before getting to a production prototype, Before that got cancelled I actually grew impatient and laid out my own crude proto PCB to advance the code development (It worked acceptably on my bench).

The final production packaging would partition the analog audio section and keep it separate from the digital front panel controls and displays that would be multiplexed/strobed being potential noise sources. The digital pots are hybrid with analog and digital inside the same package.

JR

PS: The company I was working with is getting crushed by cost effective all digital consoles. I could just about make an all-digital automatic mixer cheaper than the hybrid version but their reputation was for analog sound quality so the hybrid approach was appealing to them and their customers, but at some point lower price points overcome any digital resistance.

PPS: Back in the '70s I wrote all the software to run my mail order business (Basic running on H-11 computer platform). I even coded up a crude filter design program to help design complex multipole filters for my BBD delay designs. I printed out frequency response curves using the tab function on a dot-matrix printer.

QUESTION! How to keep all of that digital control sh!t from feeding into our itty-bitty mic level circuits...

One trick SSL used in the 4K and 6K was to "hang" the +5V CMOS supply from the +18V rail.
The +18V rail was also the +5V rail; the CMOS Ground reference, and it's return current, never touched audio ground and sat about 13V above it.
Everything coming out to a FET required level shifters.

The biggest problem I've had with low-level SPI-controlled stuff was not the SPI, but the USB 2.0 signalling from the PC to the DLP-232 USB/SPI interface.
USB 2.0 polls at about a 1 kHz rate and the RF bursts, at that rate, courtesy of rectification, are audible.
For low noise measurements I had to opto-isolate the SPI from the DLP-232 to the gain controller.
At that point my measurement floor was limited by the "instrumentation" A/D. (A PCM4222 EVAL.)

I bought the CMOS cookbook. I got halfway through the first chapter and gave up. That is about all I can contribute to this topic but I am keenly interested. There is no DIY "swiss army knife" expandable switching matrix boards available that I know of. I ended up using a pair Broadcast Tools 16x2 relay switchers in parallel for preview/modulation monitoring. Most of the boards I see available are limited to a a small number sources, like 6x2.

I mentioned this in a private email to Wayne but I thought using opto's as the switching element might be cool, useful and unique. Clickless switching is always desirable.

Digital controlled analog has actually been around for decades, while there are a few better recent choices for devices like digital gain control mic preamps etc.
-------
The problem is not what voltage digital ground is. Audio ground is basically a misnomer... there are multiple local audio 0V nodes. Grounds are for PS and chassis, not audio (IMO).
---------
For click-less switching many modern devices switch coincident with zero crossings so the step function times 0v= 0v .
-------
I see less and less value in digitally controlled analog, except perhaps as a marketing hook... but it was too little too late for my friends with an analog console company, who are slowly fading away.

JR. wrote:
For click-less switching many modern devices switch coincident with zero crossings so the step function times 0v= 0v .

I'm aware of IC solutions like the SSM2402 but no passive solutions like relay control or opto's

-------

I see less and less value in digitally controlled analog, except perhaps as a marketing hook... but it was too little too late for my friends with an analog console company, who are slowly fading away.

Yes, in a mass market kind of way. As a niche market it isn't going anywhere for a long time. API is selling 1608's by the boatload. SSL is selling a lot of their newer smaller consoles. Large format analog consoles aren't as useful anymore. The right small consoles are doing well in the marketplace.

I see less and less value in digitally controlled analog, except perhaps as a marketing hook... but it was too little too late for my friends with an analog console company, who are slowly fading away.

Yes, in a mass market kind of way. As a niche market it isn't going anywhere for a long time. API is selling 1608's by the boatload. SSL is selling a lot of their newer smaller consoles. Large format analog consoles aren't as useful anymore. The right small consoles are doing well in the marketplace.

My friends company was not large http://www.apb-dynasonics.com/but not small enough for them to all still pull a decent living after the analog market got eroded by cheap digital consoles, I hinted at them to pivot toward recording where there are still some analog purists while probably not enough to keep them in beer and chips.

JR

PS a little ironic we are discussion DSP applications for vinyl playback.

I took a look at those consoles. The analog console market is a high end only market, except for little mixers meant for stage use. The consoles they designed look like a 1990's project recording console. You can pick up consoles along those lines for pennies on the dollar.

The API is attractive because of it's sound and heritage. The SSL is attractive for it's DAW integration and sound. If the console doesn't make you think of the good old days it has to make your life easier with DAW integration.

Gold wrote:I took a look at those consoles. The analog console market is a high end only market, except for little mixers meant for stage use. The consoles they designed look like a 1990's project recording console. You can pick up consoles along those lines for pennies on the dollar.

I guess all consoles share some common elements or architecture, but their target market was live and fixed instal not recording. The APB design team was responsible for Crest consoles, and several years after Peavey bought Crest, they left and formed their own console company.

I warned them for years that digital was coming, but few inside the industry (including me) expected a digital console priced like the Behringer X32 to deliver good performance for that too low to ignore price.

The API is attractive because of it's sound and heritage.

I find it interesting how some old badges can change hands multiple times but still possess "heritage". I was involved as a consultant representing the large company buyer in a tire kicking mission (they flew me from CT to VA) in the early '80s. The company was considering buying API. At the time they had a couple $100k (?) consoles on back order (sold to customers in Japan IIRC), with very optimistic projections about how many a year they could sell in that price range. Even with the rosy sales projections that buy out didn't happen.

I can't document the full history but Paul Wolff who IIRC worked as a service technician for the second incarnation of API, ended up purchasing a bunch of the assets from bankruptcy and ended up with the name too. He started out just supporting the installed base of API consoles with repair parts, and that business selling lots of "smalls" grew to include onsey twosey big desks. Paul eventually sold that API and started another new brand (Tonelux) that was well regarded too. Apparently he later sold Tonelux too, and now just does design as an outside consultant.

The SSL is attractive for it's DAW integration and sound. If the console doesn't make you think of the good old days it has to make your life easier with DAW integration.

Now back to the regularly scheduled program.

Probably a good time to sell niche businesses with all the easy money floating around, but even that didn't help my friends company who's products were better inside than they were perceived as cool. They are still filling orders and supporting customers but sales trend arrows are pointing the wrong way.